<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <meta http-equiv="X-UA-Compatible" content="ie=edge">
    <title>genetor</title>
</head>
<body>
    
    <script>
    
        function* tell () {
            yield 'a';
            yield 'b';
            return 'c';
        }

        let k = tell();

        console.log(k.next());
        console.log(k.next());
        console.log(k.next());
        console.log(k.next());
        console.log(k.next());


    </script>

</body>
</html>